TY - JOUR

T1 - Investigating the Particle Growth in Bimodal Pt/C Catalysts by In-Situ Small-Angle X-ray Scattering

T2 - Challenges in the Evaluation of Stress Test Protocol-Dependent Degradation Mechanisms

AU - Schroeder, Johanna

AU - Pittkowski, Rebecca K.

AU - Du, Jia

AU - Kirkensgaard, Jacob J. K.

AU - Arenz, Matthias

PY - 2022/10/1

Y1 - 2022/10/1

N2 - The influence of different combinations of accelerated stress test (AST) protocols simulating load-cycle and start/stop conditions of a proton exchange membrane fuel cell (PEMFC) vehicle is investigated on a bimodal Pt/C catalyst. The bimodal Pt/C catalyst, prepared by mixing two commercial catalysts, serves as a model system and consists of two distinguishable size populations. The change in mean particle size was investigated by in situ small-angle X-ray scattering (SAXS). The comparison to the reference catalysts, i.e., the two single-size population catalysts, uncovers the presence of electrochemical Ostwald ripening as a degradation mechanism in the bimodal catalyst. Increasing the harshness of the applied AST protocol combinations by faster changing between load-cycle or start/stop conditions, the particle size of the larger population of the bimodal catalyst increases faster than expected. Surprisingly, the change in mean particle size of the smaller size population indicates a smaller increase for harsher AST protocols, which might be explained by a substantial electrochemical Ostwald ripening.

AB - The influence of different combinations of accelerated stress test (AST) protocols simulating load-cycle and start/stop conditions of a proton exchange membrane fuel cell (PEMFC) vehicle is investigated on a bimodal Pt/C catalyst. The bimodal Pt/C catalyst, prepared by mixing two commercial catalysts, serves as a model system and consists of two distinguishable size populations. The change in mean particle size was investigated by in situ small-angle X-ray scattering (SAXS). The comparison to the reference catalysts, i.e., the two single-size population catalysts, uncovers the presence of electrochemical Ostwald ripening as a degradation mechanism in the bimodal catalyst. Increasing the harshness of the applied AST protocol combinations by faster changing between load-cycle or start/stop conditions, the particle size of the larger population of the bimodal catalyst increases faster than expected. Surprisingly, the change in mean particle size of the smaller size population indicates a smaller increase for harsher AST protocols, which might be explained by a substantial electrochemical Ostwald ripening.

KW - OXYGEN REDUCTION ACTIVITY

KW - CARBON-BLACK

KW - NANOPARTICLES

KW - MEMBRANE

KW - PERFORMANCE

KW - ELECTRODES

KW - CORROSION

U2 - 10.1149/1945-7111/ac99a5

DO - 10.1149/1945-7111/ac99a5

M3 - Journal article

VL - 169

JO - Journal of The Electrochemical Society

JF - Journal of The Electrochemical Society

SN - 0013-4651

IS - 10

M1 - 104504

ER -